16521543506 has 48 divisors (see below), whose sum is σ = 27417167064. Its totient is φ = 7422573312.

The previous prime is 16521543487. The next prime is 16521543523. The reversal of 16521543506 is 60534512561.

It can be written as a sum of positive squares in 4 ways, for example, as 2912221225 + 13609322281 = 53965^2 + 116659^2 .

It is a super-2 number, since 2×16521543506² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 16521543506.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 26776910 + ... + 26777526.

Almost surely, 2^16521543506 is an apocalyptic number.

16521543506 is a deficient number, since it is larger than the sum of its proper divisors (10895623558).

16521543506 is a wasteful number, since it uses less digits than its factorization.

16521543506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1275 (or 1232 counting only the distinct ones).

The product of its (nonzero) digits is 108000, while the sum is 38.

The spelling of 16521543506 in words is "sixteen billion, five hundred twenty-one million, five hundred forty-three thousand, five hundred six".